Is a higher HRV always better?

Yes, but only in one sense. Your own average rising slowly over months, on the same device, is usually a good sign. Having a higher number than your friend means little. And a sudden jump can come from hard training or an irregular heart rhythm, which are not prizes.

Why it seems obvious

Every signal points one way. Apple describes higher variability as generally linked with better recovery. Large studies link low HRV with heart disease: in a 2013 pooled analysis of 21,988 people, those with the lowest SDNN had a 35 percent higher risk of a first cardiovascular event than those with the highest. So people chase the number up.

Is more money in the bank always better?

Sort of. A balance that has grown over the year from your own pay is good news. A bigger balance than your neighbour’s tells you little about either of you. And a sudden deposit you can’t explain is worth checking before you celebrate.

HRV works the same way. The slow climb on your own device is the earned kind. The comparison with other people is noise. The unexplained jump needs a look.

When higher is the good kind

Training raises it. Across 13 training studies with 322 people, regular exercise raised a vagal HRV measure by a moderate amount. In more than 8 million Fitbit users, people who took more steps a day had higher HRV, step by step, at every age. In a 2016 review of 27 studies of endurance athletes, resting RMSSD rose a little when training made them faster.

That’s the rise worth having: slow, on the same device, alongside better fitness, steadier sleep and fewer drinks.

When higher isn’t

Very hard training. In a 2013 trial, 13 triathletes did three weeks of overload training. Their running test results fell about 9 percent, and their weekly HRV rose more than in a group training normally. After a lighter week, performance bounced above where it started and the HRV rise reversed. The same 2016 review found overreaching came with a small rise in resting RMSSD too. A higher number in the middle of a brutal block isn’t proof you’re coping.

An irregular rhythm. HRV assumes each beat starts in the normal way. Irregular rhythms break that. A 2017 review of HRV measures warns that higher isn’t always better, because some heart conditions produce variability of their own, atrial fibrillation among them. In a study of 290 older adults, about a fifth of hourly recordings showed abnormal beat patterns that pushed HRV values up, and the people with more of them died at higher rates over seven years. A 2025 wearable validation study noted that atrial fibrillation interferes with HRV values too.

The best case for chasing it

“Higher HRV goes with lower heart risk in big studies, so pushing mine up must help.” The studies compare groups of people at one point and follow them. They don’t show that raising your own number, by any route, lowers your risk. A fit person and a person with an erratic rhythm can both post a high HRV for very different reasons. HRV researcher Marco Altini argues for using HRV in relative terms, against your own normal range, and not as a target to drive up.

The habits that raise HRV slowly, more exercise, enough sleep and less alcohol, are worth doing for their own sake. Chase those, and let the number follow.

Which spikes to check

Apple says its irregular rhythm alerts check only now and then and can’t catch every case of atrial fibrillation. Call emergency services for chest pain, fainting or shortness of breath, whatever your watch shows.